Glow switch



Dec. 14, 1943.

w. E. CARPENTER GLOW SWITCH Filed Aug. 8, 1941 lNVENTOR LEE/V727?ATTORNEY Patented Dec. 14, 1943 GLOW SWITCH Walter E. Carpenter, WestCaldwell,

N. J., as-

signor to Westinghouse Electric & Manufacturing Company, EastPittsburgh, Pa., a corporation of Pennsylvania Application August 8,1941, Serial No. 405,921

Claims.

The present invention relates to gaseous discharge devices and moreparticularly to such a device as is now known to the art as a gaseousrelay for the starting of fluorescent lamps.

In a device of this character a glow discharge is first establishedbetween the electrodes and since one of the electrodes is a bimetallicelement, it deflects under the heat of the discharge into contact withthe other electrode to shortcircuit the discharge and complete a circuitto the lamp for the purposes of starting the latter. However, thedisadvantages of glow switches of the prior art has resided in the factthat engagement of the electrodes has not lasted long enough for thelamp to be properly conditioned for starting because the bimetallicelectrode of the glow switch cooled too quickly and returned to itsnormal separated position.

It is accordingly an object of the present invention to provide a glowswitch wherein a desired time lag is provided during which theelectrodes remain in engagement with each other following extinguishmentof the glow discharge and the cessation of heat generation.

Another object of the invention is to provide for production of thedesired thermal lag in the operation of the switching electrodes of thegaseous relay by concentrating the heat of the glow discharge upon oneof the electrodes at such a region thereof that for a second or twoafter the glow has ceased, the heat will flow from this superheatedportion to the cooler portion of the electrode where most of theoperating flexure will occur, thereby keeping the contacts closed forthe desired longer period.

A further object of the invention is to increase the superheating of theswitching electrode by producing at the region of superheat a crater ofthe general type disclosed in U. S. Patent No. 2,251,568, issued August5, 1941, to D. S. Gustin et a1. and assigned to the same assignee as thepresent invention.

Among other ancillary objects of the invention is the provision of abipartite electrode of the known U-shaped or bent bimetal type, and theprovision thereon of such a crater, situated at a portion of the freeleg of the bimetal which is remote from the region of maximum bend, inorder to localize the superheat at a region where the transference ofheat by conduction to the cooler portion of the bimetal, where most ofthe bending occurs, will maintain the flexed condition thereof,prolonging the contact during which the heating current from the sourceflows with an exhaust stem Iii,

through the thermionic charge lamp.

Still further objects and features of the present invention will becomeclear to those skilled in the art by reference to the accompanyingdrawing, wherein:

Fig. 1 is a vertical sectional view of a gaseous electric relay device,showing in perspective switching electrodes in the construction of whichthe present invention has been embodied; Fig. 2 is a fragmentary detailview in side elevation of the switching electrodes taken apart from thecontainer and illustrating the open position or the switch; and Fig. 3is a similar fragmentary detail view showing the switching electrodes intheir closed position.

Referring now to the drawing in detail, the reference character l3designates generally a gaseous electric relay device of the general typeintended to be used in conjunction with a discharge lamp in such asystem as that illustrated in detail in Letters Patent Nos. 2,200,443and 2,228,210 and to which reference may be had for a more completedescription of this system. The system, as such, has not beenillustrated in the drawing herein, for the reason that such systems arenow well known to those skilled in the art, and constitute merelyillustrative examples of one application of the improved gaseouselectric relay device herein disclosed and claimed.

The gaseous electric relay device, as shown in Fig. 1, comprises anenvelope or container M which after evacuation is filled with anionizable gas such as helium, neon or the like, at a pressure approvedin practice, which may be approximately thirty millimeters, dependingupon the particular line voltage, and at the voltage of the customarycommercial source or volts, the pressure approximates fiiteenmillimeters. The device has a reentrant press portion is provided ascustomarily employed in the fabrication of incandescent lamps, and asuitable base (not shown) may be provided, if desired.

A pair of leading-in conductors ll and it are sealed into the reentrantpress, and interioriy of the envelope a supporting post is, connectedelectrically with the conductor ii, is provided, forming one or theinterior contact terminals 01 electrodes in the displate 28 of nickel,iron, molybdenum or the like, coated with an electron emissive materialsuch as the oxides of barium, strontium, etc.

The other electrode comprises a U-shaped bimetallic strip 25 having itshigh expansive side 22 on the inside of the bend, this electrode beingwelded or otherwise rigidly secured to a post 23 extending -lrom thepress it, within which it has electrical connection with the conductoriii. This electrode is of a bipartite form, one of its parts being madeof a strip of metal 2% connected firmly, as by the clamping fingers 25,to the lower end 2% of the bimetal, within which it eX- tends inwardlyand upwardly around the bend, as at 2'5, and then downwardly, in theform of a free leg 23, past the region at which the contact terminal 29of the bimetal leg 3% is adapted to be engaged with the contact terminalit hereinbefore mentioned.

Ihe strip 25 may desirably be made of zinc in the event that helium isused as the ionizable gas, but this is not intended to exclude the useof other suitable materials and gases. For example, the strip 2 may bemade of magnesium in the event that neon is utilized as the ionizablegas.

The bimetal is coated with an electron emissive substance adapted toemit a copious new of electrons, and the electrodes 2d and 32 are operable to initiate a glow discharge therebetween in known manner upon theapplication thereto of a suitable potential by means of the conductorsI? and it, which derive the same from a current source such as thatshown in the patents above enumerated.

A crater ti is provided in the surface of the electron emissive stripnear the end 2% thereof for concentrating the discharge therein to causerapid heating of the adjacent bimetal electrode leg and in pursuance ofan important feature of the instant invention this crater is disposed,as shown, at a region remote from the bend so that the superheat inducedat the crater by the glow discharge continues to affect the bend 2i andthus maintain the leg 36 in the position shown in Fig. 3, keeping thecontact terminals is and it closed, and affording a period of prolongedduration during which heating current may pass through conductors H andE8 to the thermionic electrodes of the discharge lamp, as in the systemsof the above-mentioned patents.

Referring to Figs. 2 and 3, it will be understood that as one or both ofthe opposed surfaces of the members 263 and 3B are electron emissive,the glow will be developed therebetween and the member so will swingaway from the member 2 under the action of the heat thus engendered,making the contact between the contact point 255 and the terminal Hi.

This will be effected with relative rapidit for the reason that there iswhat may be called a region of superheat developed within the concaveside of the crater 3 l and this concentration of heat radiates from thecrater against the high expansive side 22 of the member 39. Thissuperheat is dissipated with relative slowness along the member 33, andhelps to maintain the bimetal in its Fig. 3 position for an unusuallylong duraion of time, and thus retards the'breaking of contact at Zt-l 9long enough to permit the lamp electrodes to heat up to the desiredoperating temperature.

It accordingly becomes clear to those skilled in the art that a gaseouselectric relay device is herein provided with an improved constructionand arrangement of the switching elements, the operation of whichaffords a thermal lag between the making and breaking of the heatingcircuit, with a consequent heating period of adequate duration to bringthe thermionic electrodes up to the temperature required for their mostefficient action in striking the arc in the partially ionized gasbetween these electrodes of the lamp; also that the relay of thisimproved construction is adapted for use in any field in which it may beemployed advantageously by reason of the nature of the improvementsherein disclosed.

It will be clear further that the disposition of the crater at a regionremote from the bend of a U-shaped bimetal, to concentrate superheatupon the end of a leg coated with the electron emissive substance,causes the crater to cooperate with the other structural features abovedisclosed to accomplish the-objects set forth in the opening paragraphsof this specification.

Although but one embodiment of the present invention has been hereinshown and described, it is to be understood that modifications thereofbe made without departing from he spirit and scope of the appendedclaims.

claim: A gaseous electric relay device for completan electri circuitcomprising an envelope l. vided with an ionizable medium therein and airof electrodes between which a glow disarge occurs upon the applicationof a potenal thereto, one of said electrodes being a heatsponsiveelement having parts separable durlg operation to be heated by thedischarge and operable to deflect into engagement with the other of saidelectrodes to short-circuit the same and extinguish said discharge andto complete said circuit, and means carried by said heatresponsiveelectrode remote from the axis of defiection thereof to provide alocation of concentrated heat from the discharge and from which locationheat is transmitted to the axis of deflection of the heat-responsiveelectrode after extinguishment of the discharge to cause separation ofsaid heat-responsive element and a prolonged time delay in theengagement of the electrode prior to their complete separation followingcooling of said heat-responsive electrode.

2. A gaseous electric relay device for completing an electric circuitcomprising an envelope provided with an ionizable medium therein and apair of electrodes between which a glow discharge occurs upon theapplication of a potential thereto, one of said electrodes being aU-shaped heatresponsive element having parts separable durmg operationto be heated by the discharge and operable to deflect about an axisadjacent the base thereof until its free end engages the other of saidelectrodes and short-circuits the same with extingulshment of thedischarge and completion of said circuit, and means carried by the freeend of said heat-responsive electrode remote from the axis of deflectionthereof to provide a location of concentrated heat from the dischargewhich continues to transmit heat to the axis of deflection of saidheat-responsive electrode after extinguishment of the discharge to causeseparation of said heat-responsive element and a prolonged time delay inthe engagement of said electrodes prior to their complete separationfollowing cooling of said heat-responsive electrode.

3. A gaseous electric relay device for completing an electric circuitcomprising an envelope provided with an ionizable medium therein and apair of electrodes between which a glow discharge occurs upon theapplication of a potential thereto, one of said electrodes being aheat-responsive bipartite element including a metallic strip and asuperimposed bimetallic strip to be heated by the discharge end operableto cause defiection of said bimetallic strip away from said metallicstrip into engagement with the other of said electrodes to short-circuitthe same and extinguish said discharge and to complete said circuit, andmeans carried by said heat-responsive electrode adjacent the end of saidbimetallic strip and remote from the axis of deflection of the latter toprovide a location of concentrated heat from the discharge whichcontinues to transmit heat to the axis of deflection of said bimetallicstrip after extinguishment of said discharge to cause a prolonged timedelay in the engagement of the bimetallic strip with the other of saidelectrodes prior to its separation and return to superimposed positionwith said metallic strip following cooling of said heat-responsive electrode.

4. A gaseous electric relay device for completing an electric circuitcomprising an envelope provided with an ionizable medium therein and apair of electrodes between which a glow discharge occurs upon theapplication of a potential thereto, one of said electrodes being aheat-responsive bipartite element including a metallic strip and asuperimposed bimetallic strip to be heated by the discharge and operableto cause deflection of said bimetallic strip into engagement with theother of said electrodes to short-circuit the same and extinguish saiddischarge and to complete said circuit, and a crater provided in the endof said metallic strip adjacent said bimetallic strip and remote fromthe axis of deflection of the latter to provide a location ofconcentrated heat from the discharge which continues to transmit heat tothe axis of deflection of said bimetallic strip after extinguishment ofsaid discharge to cause a prolonged time delay in the engagement of thebimetallic strip with the other of said electrodes prior to itsseparation and return to superimposed position with said metallic stripfollowing cooling of said heat-responsive electrode.

5. A gaseous electric relay device for completing an electric circuitcomprising an envelope provided with an ionizable medium therein and apair of electrodes between which a glow discharge occurs upon theapplication of a potential thereto, one of said electrodes being aheat-responsive bipartite electrode of normally superimposed elementsone of which is of bimetal anchored at one end and the other element ofwhich is supported by said bimetallic element, and said bimetallicelement being free to deflect under the heat of the discharge intoengagement with the other of said electrodes to short-circuit the sameand extinguish said discharge and to complete said circuit, and a craterprovided in the end of said other element adjacent the free end of saidbimetallic element to provide a location of concentrated heat from thedischarge which continues to transmit heat to the axis of deflection ofsaid bimetallic element after extinguishment of said discharge to causea prolonged time delay in the engagement of said bimetallic element withthe other of said electrodes prior to its separation and return tosuperimposed position with said other element following cooling of saidheatresponsive electrode.

W ALTER E. CARPENTER.

